Meningococcal infections. 4. Stability of group A and group C polysaccharide vaccines.

Polysaccharide vaccines prepared from meningococci of serogroups A and C were shown to be stable for long periods when stored in the cold-for 14-26 months or more when stored as lyophilized powder and for 18 days to 9 months or longer when stored frozen in the fluid state. Lyophilized group A vaccine was unaffected by being kept at room temperature (20-25 degrees C) for 12 days or at 35 degrees C for 3 days.